The formation of slime in industrial waters is a major industrial problem since slime, which is a fungal by-product, can contaminate the end product and can cause equipment malfunction and corrosion.
The term "slime" is a broad one covering a wide range of viscous, mucous, and leathery materials found in industrial waters and on surfaces exposed to these waters. Slimes can be broadly classified as chemical or biological depending upon their cause of formation. Chemical slimes are often the result of an overabundance of a process material, usually an organic polymer, which accumulates both in water and on surfaces. Particulate matter in the water can then adhere to the polymer and may actually form the bulk of the slime mass. This invention relates to biological slimes in which microorganisms bind to surfaces and to each other. Biological slime is the result of the growth of microorganisms. In the paper industry, for example, raw materials and equipment are not sterile and water used in conjunction with such equipment is continuously being contaminated with a wide variety of microorganisms from such sources as wood pulp, chemicals, air, make-up water, and the like. The existing conditions such as temperature and pH permit the growth of microorganisms which can form slime deposits. These slime deposits are typically heterogeneous in composition and routinely contain a significant quantity of microbial cell mass and a variety of particulate material such as wood fiber, clay, pitch and the like.
Many workers have investigated the causes of slime formation in industrial waters and it is generally recognized that a broad spectrum of fungi is responsible for the formation of some slimes, particularly in paper mills that operate under acid conditions.
Historically, slime formation has been controlled by the addition of biocides to industrial waters (e.g. white water associated with the pulp and paper industry). The purpose of these biocides is to destroy or arrest the growth of some of the many organisms present in the water and thereby prevent or retard the formation of slime. Not all known biocides may be used as the biocide must not interfere with the process. Chemicals commonly used as biocides because they do not tend to interfere with the process include a wide variety of thiocyanates, sulfones, phenolics, carbamates, and isothiazolins. However, these materials can be ineffective since they are broad spectrum metabolic poisons that have no particular specificity for fungi and tend to react with bacteria associated with slimes without attacking the causative fungal organisms. In addition, many biocides are toxic to humans and wildlife and can, and often do, adversely affect the environment when the treated industrial water is returned to the environment.
Accordingly, a substantial need exists for an environmentally safe composition which effectively controls the formation of fungal slime in industrial water without interfering with the industrial process and may be used in combination with other slime control means to effectively control all slime in industrial processes.